Need some input on tuning my amp.

[RowdyMoody]

Hello,

I have a 12" Fi BTL with the UFO style magnet (it is dual 2 ohm, so I can only wire it to 1 or 4 ohms). I just installed an Alpine MRX-M240 amplifier to power it (it is wired at a 4 ohm load for 1500 watts RMS.)

I do not have an oscilloscope or any other fancy gadgetry to set all of the levels on my amp. Since installing the amp yesterday I have been incrementally creeping up my gains to a comfortable spot, it is just past half - anything beyond this and the bass overpowers all other sound too much.

I have my LPF set to 80 - I believe this is a good spot for it and have always set amps LPF to 80.

I have the bass boost all the way down

The two I am unsure of are subsonic filter and freq. I bought the amp used, and these were already set by the previous owner. I want to know what they do, and how I should set them. The subsonic filter goes from 3-30, and appears to be right in the 20 area. FREQ goes from 30-80 and is set at 55.

[hazestorm23]

For the subsonic filter its supposed to be just under what Your box is tuned to. And how do you know your lpf is set to 80? That amp just seems weird . I remember it says it does less power at 1 ohm then at 4 ohms

[RowdyMoody]

I know my LPF is set to 80 because if I look at the adjustment knob for LPF, It is set at 80 lol.

Unfortunately I don't know the tuning of my box. It is custom built, but I did not build it.

The amp is not 1 ohm stable, only 2 or 4. At 2 ohms it puts out 2400 RMS, and at 4 ohms it does 1500 RMS. Nothing seems too weird about it to me : /

[RowdyMoody]

So I am assuming subsonic filter is intended to filter out tones below what my box is tuned to? What is the purpose of this?

Also, is there a general rule of thumb or something that should be applied to how the FREQ is set? what exactly does FREQ do?

[JakeBoucher]

Subsonicfilter prevets your subs from hitting low frequencies the human ear cannot detect (you can still feel it) and keeping your subs from over exerting and getting damaged. Usually only used in ported boxes, sealed boxes use the air inside the box for "cushion" and that usually protects them from over exertion.